The present disclosure relates to an engine cooling system.
A conventionally known engine cooling system includes a water jacket (hereinafter referred to as “block-side water jacket”) provided in a cylinder block of an engine and surrounding a plurality of cylinders, and another water jacket (hereinafter referred to as “head-side water jacket”) provided in a cylinder head of the engine (see, e.g., Japanese Unexamined Patent Application Publication No. 2009-97352). Japanese Unexamined Patent Application Publication No. 2009-97352 discloses a system including two leading passages. Specifically, one of the leading passages leads a cooling liquid, that has been introduced from a water pump into the block-side water jacket through a cooling-liquid introducing passage, out of the block-side water jacket to allow the cooling liquid to flow into the head-side water jacket. The other leading passage leads the cooling liquid from the water pump such that the cooling liquid bypasses the block-side water jacket and directly flows into the head-side water jacket. When the temperature of the cooling liquid is low, as in a cold state of the engine (during warm-up of the engine), the cooling liquid from the water pump is not guided into the block-side water jacket, but is directly guided into the head-side water jacket by bypassing the block-side water jacket. This accelerates warm-up of the engine.
Japanese Patent No. 4547017 discloses disposing a water jacket spacer in a block-side water jacket, and providing the water jacket spacer with a regulation wall located close to a cooling-liquid introduction port of a cylinder block to regulate the cooling liquid flowing from the cooling-liquid introduction port to the head-side water jacket.